Packing construction for stoker plungers



R. S. RILEY PACKING CONSTRUCTION FOR STOKER PLUNGERS April 28, 1925.

Original F'iledDec. 4 1913 Patented Apr. 28, 1925.

UNITED STATES ROBERT SANFORD RILEY, 0F WORCESTER, MASSACHUSETTS,

ASSIGNOR TO SANFORD PATENT. OF

RILEY STOKER 00., LTD, 01 WORCESTER, MASSACHUSETTS.

PACKING CONSTRUCTION FOR STOKER PLUNGERS.

Application filed December 4, 1918, Serial No. 265,286. Renewed February 13, 1922. Serial No. 536,341.

To all whom it may concern.

Be it known that I, ROBERT SANFORD RILEY, a citizen of the United States, residing at Worcester, in the'county of Worcester and State of Massachusetts, have invented a new and useful Packing Construction for Stoker Plungers, of which the following is a specification.

This invention relates primarily to means for preventing leakage o fine coal dust past the feeding plunger of an automatic underfeed stoker.

With the usual construction, this fine coal gradually Works past the plunger as the latter is reciprocated, and an ob ectionable amount accummulates in front of the stoker.

It is the general object of my invention to provide a construction by which such leakage of coal around and past the plunger may be effectively prevented.

With this general object in view, my invention in its preferred form consists in the provision of a packing ring held in substantially fixed position axially and closely engaging the reciprocating stoker plunger.

An additional feature of my invention relates to the provision of means for forcing the ring yieldingly against the plunger. My invention further relates to certain arrangements'and combinations of parts which will be hereinafter described and more particularly pointed out in the appended claims.

A preferred form of my invention is shown in the drawings, in which Fig. 1 is a sectional elevation of a portion of an underfeed stoker with my improvement applied thereto;

V Fig. 2 is a sectional elevation taken along the line 2-2 in Fig. 1; and

Fig. 3 is a partial sectional elevation taken along the line 3-3 in Fig. 2 and drawn on an enlarged scale.

Referring to the drawings, I have indicated certain usual parts of an automatic underfeed stoker, including a hopper 10, a cylinder casting 11, a plunger 12 having one closed end, a crank pin 13, and a connecting rod 14 through which the plunger is mechanically reciprocated.

It is found desirable in practice that the plunger 12, should be comparatively loose in the cylinder 11 as the conditions of operation do not permit close fitting bearings.

As the piston is forced into the hopper on its working stroke the plunger becomes coated with fine coal dust, a certain portion 9f which is carried along by the plunger on its return stroke, and in the usual construction this coal gradually works past the plunger and accumulates at the front of the stoker.

To prevent this undesirable result, I have formed an annular recess 15 in the cylinder 11 and have placed therein a packing ring 16. This ring is preferably of metal, such as cast iron, and is split to permit its convenient insertion in the recess 15. The ring is formed to a smaller diameter than the plunger, and the resilience of the metal contracts the ring about the plunger.

In Fig. 2 I have shown a stud 17 formed on the end of a screw 18 and projecting into the slit betweenthe ends of the ring, thus preventing angular movement thereof. I have also found .it desirable to supplement the natural resilience of the ring by providing a plurality ofcompression springs, each acting to force the ring against the plunger. The lower springs 19 maybe retained in position by cross pins 20, and the upper spring 21 may be made adjustable by providing a threaded stop 22 above the spring. In the particular construction shown in the drawings, the position of the hopper is such that the spring 21 must be placed at an'angle, requiring a spacing block 23 between the spring 21 and the ring 16.

The outer or right-hand edge of the ring 16 as seen in Fig. 3 is beveled so that any coal dust forced outward against the ring may increase rather than decrease the pres sure of the ring against the plunger. The left-hand face is shown as normal to the surface of the plunger, enabling it to act as an efficient scraper.-

I have also indicated the outer or righthand wall of the cylinder recess as inclined to correspond to the bevel of the ring, so that the tendency of the plunger to carry the ring along with it as it is withdrawn from the hopper will cause a slight wedging action, tending to force the ring more closely against the plunger.

In the drawings it will be noted that the I rings 16 are loosely, mounted in the annular recess so that they may be yieldingly selfcentering upon the piston. These yielding rings form no effective part of the bearing for the piston which is slidable upon the continuous inner bearing-surface of the cyl- I inder 11. The 'rin 's 16 center themselves type mounted in grooves in the plunger are not practicable as they would at times be beyond the end of the cylinder 11. By mounting the ring 16 in thefixed cylinder 11 instead of in the movable plunger 12, I provide a packing ring closely adjacent to the end of the cylinder and one which at all times remains in this position.

By the use of my improved construction the objectionable leakage of coal dust past the plunger is effectively eliminated.

Having described my invention, it will be evident that changes and modifications can be made therein by those skilled in the art without departing from thespirit and scope thereof as set forth in the claims, and I 0 not wish to be otherwise limited to the de- I tails herein disclosed, but what I claim is An automatic underfeed st'oker having, in combination, a coal hopper, a cylinder opening into the lower portion of said hopper and having an annular recess adjacent its inner end, 'a iston loosely slidable in said cylinder, mec anical means to reciprocate said piston, and means to prevent the escape of coal past said piston, said means comprising a split metal ring positioned in said recess and yieldingly engaging said piston, said ring and recess having associated inclined walls cooperating to force said ring against said piston as the latter moves away from said hopper.

In testimony whereof I have hereunto affixed my signature.

ROBERT SANFORD RILEY. 

